Helicopters B

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mrsteven
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Re: Helicopters B

Post by mrsteven » March 11th, 2013, 7:27 pm

fifty_missions wrote:On testing a given rubber motor, wind the motor (off the helicopter) to destruction while counting the winds and tracking the torque. The rule of thumb is that the safe maximum winds and torque will be 20% less than that at the point of destruction.
20%? Thats alot. Last 2 years I was running the rubber 1 wind (with a 10:1 ratio) under breaking. 20% leaves a lot of potential winds unused
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Re: Helicopters B

Post by _HenryHscioly_ » March 31st, 2013, 12:06 am

Is using a drill to wind rubber band practical?

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Re: Helicopters B

Post by chalker7 » March 31st, 2013, 11:39 am

_HenryHscioly_ wrote:Is using a drill to wind rubber band practical?
It's not recommended. A big component of winding is knowing exactly how many winds you have put on the rubber band as well as the "feel" of how much torque/how close the rubber band is to breaking during winding. Using an electric drill obscures both of those pieces of information.
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Re: Helicopters B

Post by retired1 » April 2nd, 2013, 8:10 am

It would only be rational if you were doing the winding on a torque meter. I am old school, I like the 10:1 winder.

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Re: Helicopters B

Post by hogger » April 2nd, 2013, 1:58 pm

What is the reason why one uses torque meter in this event? I'm not an expert but when I did wrightstuff, the main reason for torque meter was to be able to have better control of the height that the plane would reach with the torque reading. The torque reading gives you sort of the instantaneous power being applied to the prop of the plane, and it approximately will control the maximum height of wrightstuff plane. In this event, if there is no obstruction before the ceiling, it seems that you want to wind the rubber to the max and does not care too much how high it would get, thus one should not care too much about initial torque? Probably there are more to it than that, I guess that is why I am asking.

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Re: Helicopters B

Post by mrsteven » April 2nd, 2013, 2:07 pm

To know the breaking point. Before the rubber band breaks, the torque spikes very noticably. If you use a torque meter, you can see that spike and stop winding before the breaking point.
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Re: Helicopters B

Post by hogger » April 2nd, 2013, 2:21 pm

Ahh yes. It is another indication along with the "feel" that the winder must sense before the break and reducing the length or the stretch until you run out of stretched rubber. Also probably a good way to get consistent maximum winding by giving feedback to confirm what you are sensing in the tension and not to prematurely reduce the stretch until the torque gets to certain point. If that makes any sense.

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Re: Helicopters B

Post by chalker7 » April 2nd, 2013, 6:53 pm

hogger wrote:What is the reason why one uses torque meter in this event? I'm not an expert but when I did wrightstuff, the main reason for torque meter was to be able to have better control of the height that the plane would reach with the torque reading. The torque reading gives you sort of the instantaneous power being applied to the prop of the plane, and it approximately will control the maximum height of wrightstuff plane. In this event, if there is no obstruction before the ceiling, it seems that you want to wind the rubber to the max and does not care too much how high it would get, thus one should not care too much about initial torque? Probably there are more to it than that, I guess that is why I am asking.
Beyond simply using them to predict the breaking point for a motor, there is another use for torque meters. We talked about it quite a bit last year, here's a good post to get you started: http://scioly.org/phpBB3/viewtopic.php? ... 45#p191095
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Re: Helicopters B

Post by Skink » April 2nd, 2013, 7:03 pm

How do you troubleshoot a significant (20% reduction...ouch) decrease in flight time? Is it a result of rubber bands getting old? Our rubber bands have a few whitish splotches. I assume those are blemishes of some kind. Does that mean replace them? We typically wait until they begin to tear somewhere before discarding them. Thanks.

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Re: Helicopters B

Post by mrsteven » April 2nd, 2013, 7:09 pm

Skink wrote:How do you troubleshoot a significant (20% reduction...ouch) decrease in flight time? Is it a result of rubber bands getting old? Our rubber bands have a few whitish splotches. I assume those are blemishes of some kind. Does that mean replace them? We typically wait until they begin to tear somewhere before discarding them. Thanks.
Tan sport Rubber for helicopters lose elasticity after a few flights. I wouldnt use them past 4 flights. I noticed last year that the 2nd flight (occasionally third) on each rubber band yielded the best flight time of the bunch. Stretched out enough to be more profitable but not so much it loses the ability to be effective. Switch out motors often
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